Cascade and staggered dielectrophoretic cell sorters

Abstract

We have developed two new microfluidic cell sorters based on conventional negative dielectrophoresis (DEP) for continuous flow operations. The first is a cascade configuration sorter designed to increase purity of isolated target cell. The second has two staggered side channels in opposite side walls to increase sample throughput without compromising enrichment factor. Particles (carboxylate microspheres) of different sizes were first used to demonstrate the feasibility of the present DEP sorters for cell isolation. Then biological cells, i.e. human prostate cancer cell line LNCaP and human colorectal cancer cell line HCT116 were used to test the performance of the DEP sorters. In the present work, applied voltage was in the range of 0-20 V(p-p) , and frequency was from 0 to 10 MHz. Comparing to a single side channel DEP cell sorter, the isolation purity was improved from 80 to 96% by a single cascade sorter and the sample throughput was increased from 0.2 to 0.65 μL/min by a single staggered side channel sorter. In this article, we report the cell sorter designs, cell separation and enrichment factors.

Characterization of a hybrid dielectrophoresis and immunocapture microfluidic system for cancer cell capture

“…In the high-conductivity cases, the pDEP response and crossover frequency regions were fit well; the magnitude and frequency dependence, as well as the fit value for C membrane , were similar to those previously reported for other cancer cells [54][55][56]. Yang et al reported on DEP separation of LNCaPs from colorectal cancer cells, but used a higher conductivity media (σ m = 300 mS/m) at which LNCaPs experienced nDEP even in the MHz range [44]. Although we did not perform DEP characterization experiments at this conductivity, our model does predict similar nDEP behavior in those high conductivity and frequency ranges.…”

“…A majority of DEP cancer cell isolation techniques use model cancer cell lines spiked in buffer media or diluted blood; such techniques include DEP flowfield fractionation (DEP-FFF) [33][34][35][36], insulative and contactless DEP [37][38][39][40], and streamline separations using angled electrodes [41][42][43][44]. These studies separate cancer cells from other blood constituents based on their differences in DEP response in a specific applied frequency range.…”

“…This binary separation mechanism makes DEP an attractive tool for cell separation, as DEP requires no biochemical treatment or labeling to achieve high capture efficiency and purity. However, to date, studies using DEP methods for CTC capture have only reported high capture performance for model cancer cell lines spiked in preprocessed blood with concentrations ranging from one cancer cell per 10 4 -10 6 blood cells [33,34,36,39,40,42,44]. The commercially licensed ApoStream ™ (ApoCell) system, which uses DEP-FFF, has reported capture efficiencies in the range of 50-80% for ovarian and breast cancer cell lines spiked in peripheral blood mononuclear cells (PBMCs) with concentrations as low as one cancer cell per 10 6 blood cells, but noted that efficiency decreased after running samples through the system multiple times to increase capture purity [35].…”

Separation of tumor cells with dielectrophoresis-based microfluidic chip

“…This is defined as the ratio of target cells deflected towards the side channel to the total number of target cells flowing through the inlet. 42 g ¼ A=ðA þ BÞ;…”

“…This can be realized using a cascaded and staggered DEP sorter (demonstrated by this group) for increasing target cell purity and throughput. 42 Additionally, enriched target cells remain unaltered and can be easily cultured for further testing and analysis. Providing an improved method for early detection of pre-metastatic tumor is an important clinical goal to achieve because progression of metastatic cancer rapidly decreases survival rates.…”